


Little Moon

by FullOfBoredom



Category: Undertale (Video Game)
Genre: M/M, Nightkiller - Freeform, killermare - Freeform
Language: English
Status: Completed
Published: 2021-01-24
Updated: 2021-01-24
Packaged: 2021-03-16 02:07:24
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,339
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28948662
Author URL: https://archiveofourown.org/users/FullOfBoredom/pseuds/FullOfBoredom
Summary: “I know I make you speechless, but this is unusual even for you.” Killer leaned down to kiss the curve of Nightmare’s neck. “It’s almost like you’re scared.” He whispered it along the bones, the tiny gasp flaring up the heat in Killer’s body.“I am.”
Relationships: Sans/Sans (Undertale)
Comments: 11
Kudos: 70





	Little Moon

**Author's Note:**

> Very brief setup. Made in an AU where Dream defeats Nightmare and becomes god of both positivity and negativity, but Nightmare barely lives. He’s close to mortal (uncorrupted) and living alone in a random AU, but bad guys squad finds him and just chill a lot since they all realized that they might be the only friends they had. Established Killermare.

“What’s up Nightlight?” Killer closed the door behind him. He’d re-picked up the habit pretty quickly when the rest of the guys started making themselves at home in the small house. Nightmare sat at the edge of the bed, leaning back on his arms. His face was flushed purple, very nervous and opposite of his body language. It was amazing how much the corruption had hid or eradicated in his boyfriend.

“I wanted to speak with you alone.” His voice was soft, not the piercing presence of a king, not the sharp but clear voice audible at every volume. This felt close, private. Nightmare’s less aggressive side was new to all of them. 

“Well you got my attention. Not that you don’t have it all the time anyway.” Killer’s smile climbed into something sly. He cupped a purple cheek in his right hand, the curve of Night’s hip in his left. His thumb rubbed softly into the ecto he could feel underneath (he’d gotten a peek when Nightmare had leaned back, a thin line of purple barely visible under his clothes), wondering why he was summoned when this didn’t feel like that kind of night. “So what’s up Boss?” 

He laughed at Nightmare’s annoyed pout. He leaned in to kiss it happily. His hand tilted back Night’s head, mouth opening to deepen the little kiss, though he didn’t delve too deep. Killer wouldn’t be able to stop if he got too far.

“I told you not to call me that.” Nightmare’s eyes wouldn’t meet his. “I’m not the boss of any of you anymore. I have nothing but my life, and barely that.” His hands rested at the base of his hood, playing with the strings to tighten it. “I don’t want you to think of me as some lord you must obey. Especially not now.”

Killer pushed him back, hovering over his body. He pinned Night with just his stare.

“I obey you when I want to. Nothin’ more, nothin’ less. You just happen to be a little more… _academic_ than me.” Not smart, never smart. He and Dust both had a long life full of planning and killing. Dust had him beat in pure power, but his head was screwed on a little tighter and that edge made a lot of difference. He could _plan_ , but the long overarching consequences of actions were more Nightmare’s game.

Night still wouldn’t meet his eyes.

“I know I make you speechless, but this is unusual even for you.” Killer leaned down to kiss the curve of Nightmare’s neck. “It’s almost like you’re scared.” He whispered it along the bones, the tiny gasp flaring up the heat in Killer’s body.

“I am.”

That drew Killer up to look Nightmare in the face. He could see tears building in his eyes, the first one sliding over an ivory cheek.

The idea of Nightmare being terrified of anything besides one of their own being killed struck him as novel, interesting. Part of him wanted to tease him. The other part, the louder part that gathered Nightmare into his arms for comfort, knew that if it was this upsetting, it was worth him worrying over as well.

“Ain’t nothing taking you from me. And the guys won’t leave. We’ve all gotten used to each other’s weirdness. The rest is small potatoes. Nothing to worry about, no matter what you’re gunna say.”

Nightmare’s legs drew up, trying to curl into a ball in Killer’s arms, so he adjusted to a bridal carry to let him wind in on himself, but still solidly in his grasp. He laid his head against Killer’s arm, and Killer could hear the softest of sobs. He didn’t know if Night always cried this softly or if he was putting on a braver face even in this form. He wasn’t prepared for when his moon looked up at him.

Wide teary eyes, face streaked in lavender trails, brows drawn together in sorrow, and a pained frown, but still on the cutest face he’d ever seen. He’d stared so hard he almost didn’t absorb what Night said.

“I’m _pregnant_.”

His body reacted on a five second delay. What? His head tilted, eyes squinting in confusion. He was pregnant? I mean, okay, that’s odd, but…wait, how did he…? Had he cheated on him? No, his moon would never. But that meant…

“It’s mine?” His voice sounded a million miles away. Nightmare turned away, a little huff of anger.

“Who else’s would it be?” He curled up tighter in Killer’s grasp. “In even my worst case scenarios, I thought you’d at least know that.” Killer’s face still hadn’t changed from confusion. “Do you think I was SLEEPING AROU-” Nightmare squeaked when his legs were dropped, a hand sliding up from his pelvis.

Killer caught the hem of Nightmare’s shirt with his thumb, dragging it up along the smooth purple ecto. He pushed it as far as it would go before his vision refocused.

A very tiny souling floated in the center of him, a bit below Nightmare’s apple soul. It vibrated when Killer laid his hand over the tiny heart.

This was real. Nightmare was carrying his baby, a little soul made of just them.

“Holy shit.” That was all his brain could think to say. Killer laid Nightmare back on the bed, climbing over him again, stopping his face just above his stomach. He put his head down right over the souling. He could feel the little life pulsing under his skull, and his own eyes had already started to leak red laying there. Killer’s brain only came to under Nightmare’s hand cradling his skull. 

“Are you alright?” Killer’s hand laid over Night’s, turning himself over to gently kiss the back of Nightmare’s hand. He left a trail of kisses up his entire arm until he’d reached bright purple cheeks, and then he kissed all over his face. By the time he’d softly kissed his mouth, Nightmare was already crying and clinging to his hoodie. Killer’s tongue slowly tangled with Night’s. The dragging of one over the other sparked soft groans from both, Killer’s hands caught between cradling Nightmare’s face and his child. 

“Moon.” He couldn’t move away. His universe had its center, hopelessly trapped in his moon’s orbit until his dying breath. For just a moment, the world ceased to be, held in existence solely by the gravity of his devotion.

“Soul.” God, he’d trade his away with just a word from that smile. He’d been willing to die for just a glance from those violet eyes, the same ones that now never left his side. He kissed each eyelid.

“I love you.” They’d slipped out, straight from the depths of his heart. 

“I love you too, my darling Soul.” He felt a finger trace the edges, Nightmare’s fingers so wonderful over his heart. “I…I wasn’t sure how you’d take it. We’ve never talked about children.” Killer’s eyes slipped shut under the attention.

“I had a really bad time with the human one, but if it’s half you, then I’m already in love with ‘em.” He opened them again when Nightmare sniffled. His poor moon had started to cry again. “I’m sorry! I didn’t mean to make ya cry.” He quickly clanked over each of Night’s falling tears until he heard a laugh under the sobs.

“They’re happy tears Soul. No need to apologize.” He captured Killer’s mouth in a kiss. When they could breathe again, Killer rolled them onto their sides, burying his face into Nightmare’s chest and pulling him close.

“Got any names thought up Nightlight?” He purred into Night’s sternum when the other massaged his skull.

“I hadn’t the time, I was too worried about what you’d say.” 

“Told ya, ain’t nothing taking ya from me. Mmmm, do you know of any little moons out there?” He could feel a chuckle rumble up from Night’s chest.

“Plenty come to mind. I hadn’t considered them…”Killer felt the hands on his head still. Nightmare breathed out softly.

“Deimos.”


End file.
